Process for the preparation of aluminium hydroxy halide powders

ABSTRACT

For the working up of aqueous aluminium hydroxy chloride or bromide solutions to powdery, colourless clear water-soluble products the process of the spray drying by means of drying gas introduced in parallel flow is suitable, if the following conditions are adhered to: temperature of the drying gas at the dryer entrance 205* to 500*C, relative moisture of the gas leaving the dryer 20 to 40 %.

United States Patent Nov. 18, 1975 Danner et al.

PROCESS FOR THE PREPARATION OF ALUMINIUM HYDROXY HALIDE POWDERS Inventors: Max Danner; Martin Krieg, both of Gersthofen; Klaus Matschke, Burgkirchen, Alz, all of Germany Hoeehst Aktingesellschaft, Frankford am Main, Germany Filed: Dec. 19, 1973 Appl. No.: 426,309

Assignee:

Foreign Application Priority Data Dec. 3, 1972 Germany"; 2263333 US. Cl 23/293 A; 423/462; 424/68;

' 159/48 R Int. Cl. C01F 7/48; B01D 1/18 Field of Search 423/122, 495, 462; 424/68;

23/313 R, 293 A, 293 R; 159/48 R, 4 R;

References Cited UNITED STATES PATENTS 10/1960 Messina 424/68 FOREIGN PATENTS OR APPLICATIONS 2,152,509 6/1972 Germany 23/293 OTHER PUBLICATIONS Gardiner et al., Fiat Final Report No. 788, Apr. 3, 1946, pp. 1 to 11.

Primary Examiner-Norman Yu'dkoff Assistant Examiner-S. J Emergy Attorney, Agent, or Firm-Connolly and Hutz [57] ABSTRACT 2 Claims, No Drawings PROCESS FOR THE PREPARATION OF ALUMINIUM HYDROXY HALIDE POWDERS The present invention concerns a process for the 5 preparation of aluminium hydroxy halide powders.

Basic aluminium halides are being used increasingly in the cosmetic industry in the form of anti-perspirants,

shaving lotions and medicinal cosmetic preparations.

The aluminium salts are preferably processed in the form of powders. H v

The basic aluminium halides are obtained in the various processes of preparation at first as aqueous solution (for example, German, Patent Specification 1,174,751). The solutions are then evaporated, in genera] by making into scales on drumdryers, which process should be carried outunder mild conditions in order to avoid further, partly irreversible,.splitting off of water from the basic salts,- since the solubility and colour are thereby impaired. The scaled aluminium hydroxy halide solutions in spray dryers (for example German Offenlegungsschrift 2,152,509). Products which are very different in quality and colour are obtained; the conditions of work must be laid down empirically.

It has now been found that powders with the desired chemical and physical properties are obtained in always the same quality from aqueous solutions of basic aluminium halides simply and in one single process step, when operating in a spray dryer, -under definite conditions concerning the water available during drying. I

The present invention, therefore, provides a'process for the preparation of colourless,water-soluble aluminium hydroxy chloride or bromide powders of the formula Al (OH),,X wherein X is the halogen, n repre- 40 sents a number between 3 .0 and 5.1 and 2 represents a number between 3.0 and 0.9, and thesum n z is always equal to 6, from aqueous solutions of basic aluminium chlorides or bromides with an atomic ratio of Al:X=0.66: l to 2.2: l,preferably 1.9 l to 2.1 1,

wherein 20 to percent by weight aluminium salt solutions are sprayed into a spray dryer, and the drying gas introduced in parallel flow is kept at the dryer entrance at a temperature of 205 to 500C and at the dryer outlet the relative moisture is adjusted at 20 to 50 It was surprising and not to be foreseen that, for drying in the spray dryer careful adherence to narrow temperature limits is not important as in the case of the drying on drum dryers, but the quality of the end product depends here exclusively on the moisture conditions prevailing within the dryer. According to the method of the invention taking into account this'fact it is, therefore, possible to prepare aluminium .hydroxy halides under optimum conditions and, therefore, in

optimum quality. 1 1

The products differ from those obtained byv known processes in that they arealways colourless and form a clear solution in water, further, by their higher apparent density and the slighter tendency to forming dust. The spherical shape of the single particles and the favourable grain spectrum proveespecially advantageous in the preparationof cosmetic mixturessince these preparations have a remarkably low viscosity in comparison to those which have been prepared from products dried on drums.

The aqueous solutions of aluminium hydroxy chlorides or bromides to be worked up according to the invention are prepared according to known processes, for example that described in the German patent specification 1,174,751. They should contain 20 to 50 by weight of the salt, in which aluminium and halogen are present in the atomic ratio of 0.66 1 to 2.2 l, preferably 1.9 l to 2.1 1. This ratio is almost unaltered in the dried powder. The process is carried out in such a way that the aqueous aluminium salt solution is sprayed into a gas stream blown through a. spraying dryer via twosubstance nozzles ;or perforated discs with corresponding speed of rotation and number of apertures. Suitable two-substance nozzles are, for example those, which are Operated with a bore of 3 mm with an air pressure of 10 atmospheres.

The dryer is fed with hot gases, preferably with hot air. Gas temperatures of admission of from 205 to 500, especially from 290 to 350C, have proved successful. The process is especially economical if combustion gases are available for the heating of the drying gas.

For the success of the process it is essential that before leaving the spray dryer the product is always in contact with an atmosphere the relative moisture of which is in the region of between 20 and 40 The temperature, at the dryer exit, of the gas-solid mixture leaving the dryer'should be preferably 50 to 150C. This is achieved by fixing the ratio of drying-gas to the quantity of salt solution (ie. to the water quantity contained in the solution) per time unit by using the formula for calculating the relative air moisture, according to which the following apply:

1. relative moisture of the waste gas gram water/m waste gas gram water at saturation/m waste gas P 100 relative moisture of the waste gas in which x water content in kg/kg dry air P total pressure of the system P saturation pressure of the steam at the temperature of the waste gas.

However, also a part of the moisture necessary can be added to the system in the form of moistened drying gas (for example, by blowing in steam). The dosing in of steam is especially advantageous for setting the relative outgoing air moisture.

For example, the necessary quantity of drying gas with a certain temperature can be easily determined by calculation with a waste gas temperature given in advance and relative moisture of the waste gas given in advance for a desired throughput of salt solution, whereby the quantity of water necessary for the saturation is to be taken from relevant tables. A relation for the remaining values-results from the heat economy valid for the dryer:

in which Q, represents the quantity of heat which is contained in the drying gas Q represents losses of heat by radiation,

4 m in length was used as dryer. As drying gas air was used. The salt solution to be sprayed was fed in by means of a pump to a 2-substance-a tomizing nozzle or a rotating perforated disc. The product bore of the 2- Q represents the quantity of heat contained in the 5 substance nozzle was 3 mm, the atomizing air pressure waste gas l atmospheres. The perforated disc of titanium had a Q, represents the evaporation heat for the quantity of diameter of 300 mm and a speed of 18,000 revoluevaporated water tions/minute. 136 kg of 50 by weight aqueous solu- In the equation Q, or Q may be replaced by the tion (25C) of aluminium hydroxy chloride (AlzCl products M 8 T, or M T wherein M represents the 10 atomic ratio 2: 1) were sprayed hourly through the 2- mass and 8 the specific heat of the drying gas; T and T substance nozzle at a spraying air pressure of 10 atmoare the respective temperatures. Q is a characteristic spheres. As drying gas 720 Nm air/h were blown constant to be determined for the dryer (only depenthroughthe dryer in parallel fiow. At the tower endent on the temperature conditions chosen in the trance the drying gas had a temperature of 320C and dryer), Q, is the total quantity .of heat for evaporating a water content of 1 g/m. the sprayed water calculated from the known evapora- .The drying gas left the tower together with the tion heat of water. sprayed product at a temperature of 80C and a mois- In the first approximation, for example, from M (the ture content of 75.8 g of H O/kg, from which a relative drying gas quantity calculated according to formula 1) moisture of 23 is calculated. The product was sepathe temperature T wanted is obtained from the relarated in a cyclone. tion The basic Al-chloride obtained was colourless and M 5 (I I 72) Q3 clearly water-soluble. The Cl-content was 16.8 corto responding to a composition of Al (OH) Cl 3 H O.

Q Q3 25 EXAMPLES 2 to 10 T1: 72+ M a In the apparatus described in Example 1, 50 by weight of aqueous solutions of aluminium hydroxy chloride (or bromide in Example 10) were worked up The pfodufits Obtamed which have the adlantageous to powders. The working conditions and the results are P p f above are used P y the l summarized in the'following table. From the compari of cosmet1cs 1n aqueous or alcohol c preparatlons or 1n fi examples 2 to 4 i can b Seen h the products f y P y be F f y h formula the process are not satisfactory if the relative moisture 2 (OH)IIXZ9 Wherem X 15 Chlorme bfomme, P- of the waste gas is outside the limits required. The baresents a number between 3.0 and 5.1 and z represents rometer reading was 7 0 ton Ex. Throughput Dry gas (air) Properties of the dried product of Al-salt Quan- Temp. Temp. g H2O/ g H2O! rel. halogen water aqueous solution tity enoutlet kg kg moiscontent content solution 50% by (m/h) trance drying drying ture m accordcolour weight (C) (C) gas at gas at exit ing to (kg/h) enexit (7:) (7r) Al (OH) trance X.m H20 2 58"" 720 220 100 1 32,2 5 17,5 1,5 yellow largely insoluble 3 72 720 280 95 1 7,5 17,4 1,5 yellow strong deposit 4 69 720 220 77 l 3 8,4 14 17,3 1,6 yellowish weak deposit 5 44 554 210 100 124"" 155 20 16,7 2,1 colourless clear 6 52" 5 5 3 209 96 124* 161 24 16,2 2,5 colourless clear 7 61 N 570 210 102 227 270 28 16,2 2,5 colourless clear 8 74" 680 210 70 43,5"" 87 40 16,0 2,6 colourless clear 9 92 720 210 60 1 51 39 15,9 2,7 colourless clear 10 92 720 210 60 l 51 39 30,5 2,4 almost clear colourless chloride 'bromide 'Z-substance-nozzle "perforated disc "steam was added to the drying gas '10 g product in ml of water of 20C.

a number between 3.0 and 0.9, and n z 6. This for- What is claimed is: mula represents a simplification in so far that the basic 1. Process for the preparation of colourless, watersoluble aluminium hydroxy chloride or bromide powaluminium halides probably constitute polymeric compounds. The compounds contain, furthermore, a variable number of water molecules which are bound in complex manner or as-water of crystallization.

The following examples illustrate the invention.

EXAMPLE 1 An atomizing tower, consisting of a cylindrical part 4 m in length and 1.6 m in diameter and a conical part 2 ders of the formula Al OH) X wherein X is the halogen, n represents a number between 3.0 and 5.1, and the sum 11 +2 is always equal to 6, from the aqueous 20 to 50 by weight solutions of basic aluminium chlorides and bromides with an atomic ratio of Al X 0.66 1 to 2.2 1, wherein aluminium salt solutions are sprayed in a spraying dryer, in which the drying gas is introduced in parallel flow and has a temperature of ratio of the rate of the drying gas and the rate of water, contained in the aqueous aluminium salt solution and the inlet gas, is chosen in such way that the off gas of the dryer has a relative humidity in the range of to 40% and the outlet temperatures are between 50 and 150C.

2. Process for the preparation of colourless, watersoluble aluminium hydroxy chloride or bromide powders of the formula AI (OH),,X wherein X is the halogen, n represents a number between 3.0 and 5.1, and the sum n z is always equal to 6, from the aqueous 20 to 50% by weight solutions of basic aluminium chlorides and bromides with an atomic ratio of Al X 0.66 l to 2.2 1, wherein aluminium salt solutions are sprayed in a spraying dryer under conditions that the expression rate of added (evaporated) water [kg/min] rate of inlet air [kg/min] and the inlet dry gas has a temperature of 290 to 500C., and the outlet gas temperature is between 50 and C. 

1. PROCESS FOR THE PREPARATION OF COLOURLESS, WATERSOLUBLE ALUMINIUM HYDROXY CHLORIDE OR BROMIDE POWDERS OF THE FORMULA AL2(OH)NXZ, WHEREIN X IS THE HALOGEN, N REPRESENTS A NUMBER BETWEEN 3.0 AND 5.1, AND THE SUM N+Z IS ALWAYS EQUAL TO 6, FROM THE AQUEOUS 20 TO 50 BY WEIGHT % SOLUTIONS OF BASIC ALUMINIUM CHLORIDES AND BROMIDES WITH AN ATOMIC RATIO OF AL :X==0.66:1 TO 2.2:1, WHEREIN ALUMINUM SALTS SOLUTIONS ARE SPRAYED IN A SPRAYING DRYER, IN WHICH THE DRYING GAS IS INTRODUCED IN PARALLEL FLOW AND HAS A TEMPERATURE OF 290* TO 500*C AT THE DRYER ENTRANCE AND WHEREIN THE RATIO OF THE RATE OF THE DRYING GAS AND THE RATE OF WATER, CONTAINED IN THE AQUEOUS ALUMINIUM SALT SOLUTION AND THE INLET GAS, IS CHOSEN IN SUCH WAY THAT THE OFF GASS OF THE DRYER HAS A RELATIVE HUMIDITY IN THE RANGE OF 20 TO 40% AND THE OUTLET TEMPERATURES ARE BETWEEN 50* AND 150*C.
 2. Process for the preparation of colourless, water-soluble aluminium hydroxy chloride or bromide powders of the formula Al2(OH)nXz, wherein X is the halogen, n represents a number between 3.0 and 5.1, and the sum n + z is always equal to 6, from the aqueous 20 to 50% by weight solutions of basic aluminium chlorides and bromides with an atomic ratio of Al : X 0.66 : 1 to 2.2 : 1, wherein aluminium salt solutions are sprayed in a spraying dryer under conditions that the expression 